MemcachedMemcached is a free & open source, high-performance, distributed memory object caching system, generic in nature, but intended for use in speeding up dynamic web applications by alleviating database load.
DockerDocker is a Linux container runtime. Docker complements LXC with a high-level API which operates at the process level. It runs unix processes with strong guarantees of isolation and repeatability across servers.

Warning Recommended: Memcached for Wordpress tutorial - how to reduce your server load and improve website speed while using it on the server with Plesk.